Smartphones and tablet devices have become popular with a remarkable tendency of higher definition of image displaying and higher functionality of touch sensing. In many implementations, smartphones and tablet devices include a display touch panel having control circuitry which may include a plurality of integrated controllers (ICs). For example, control circuitry may include one or more of a display driver, a touch controller and a sequence controller or a monolithic IC incorporating the same. A sequence controller may be implemented as a microcontroller and may be configured to perform setting of parameters of gamma correction to the display driver, and execution of a program to calculate the touch coordinates from data obtained from the touch controller.
In many current implementations, a display driver includes a sub-processor which performs setting various parameters onto the display driver and the touch panel controller by executing programs. The programs and parameters are supplied from the main controller to the sub-processor.
In various embodiments, the types and numbers of parameters and the sizes of the programs tend to be increased due to higher definition of image displaying and higher functionality of touch sensing. This considerably increases the communication traffic between the sub-processor and the main controller, causing an increase in the communication time or an increase in the cost to reinforce the communication interface. Hence, there is a need for a display driver having decreased communication time and/or communication interface requirements between components of the display driver.